The disease process of diabetes has been studied extensively, and its debilitating effects on its victims and the financial drain on the healthcare system are well documented. The actual disease of diabetes can be controlled with medication, but the side effects and secondary complications of the disease are what cause the real damage to its victims. Foot ulceration is the single most common cause for hospitalization of diabetic patients. Foot ulceration occurs as a result several factors, but the most important cause is the lack of patient awareness of the potential problem and their subsequent lack of attention and care of the cause of the foot ulcers. Peripheral neuropathy plays a role in diminishing the feeling in the patient's foot, and incorrectly providing the patient with a sense of well-being through a lack of any pain or sensation.
Ulceration on the sole of the foot is most often preceded by an increase in skin surface temperature at the pre-ulceration and ulceration site. The ADA, as well as other clinical practice guidelines, suggests that diabetic patients with neuropathy should monitor their feet for temperature changes that could indicate that inflammation is present and an ulcer could develop. However, just informing a patient that due to their neuropathy they are at higher risk for foot ulceration, without providing them a simple means to monitor the temperature and condition of the soles of their feet (which they likely can't see or even touch) is not effective.
As described in U.S. Pat. No. 5,678,566 to Dribbon, thermography has been identified as a potential diagnostic tool is in the treatment of the diabetic and insensate foot patient. Unable to feel pain, the insensate foot patient is at great risk of foreign body infiltration, shoe irritation and the trauma caused by simple ambulation. It has been found that typically only after blood appears on the sock or shoes will such a patient seek treatment, but by that time serious damage may have already occurred. Research has been conducted with respect to the effectiveness of contact thermography as a diagnostic tool to detect areas of tissue damage and inflammation which can lead to ulceration on the plantar surface of the foot. See Stess et al.: “Use of Liquid Crystal Thermography in the Evaluation of the Diabetic Foot,” Diabetes Care., 9(3):267-272 (May-June, 1986); Benbow et al.: “The Prediction of Diabetic Neuropathic Plantar Foot Ulceration by Liquid-Crystal Contact Thermography,” Diabetes Care, 17(8)835-639 (August, 1994); and Dribbon: “Thermography and Diagnosis,” Pain Practitioner, the Quarterly Newsletter, pp. 3-4. As explained in these articles, tests indicate that contact thermography is a viable diagnostic tool which is capable of providing an indication of abnormalities in the diabetic foot even before the occurrence of ulceration or other tissue damage.
There have been a number of prior patents filed to measure visual pattern of infrared heat emissions from a particular area of the body employing thermochromic liquid crystal technology (See U.S. Pat. No. 5,124,819, Davis, U.S. Pat. No. 5,678,566, Dribbon, U.S. Pat. No. 4,327,742, Meyers et. al., U.S. Pat. No. 4,327,743, Katz).
Unfortunately, the mechanisms and devices used in each of these prior uses of LCT and the devices themselves were not tailored specifically to enable a diabetic patient to use the device in the home environment on a daily basis to monitor and examine the planter surface of the foot. Specifically, these prior uses failed to optimize the device so that (i) temperature differences represented by color changes would be readily apparent to the home user and not require the skill of a physician to interpret results and (ii) the design of the device itself would facilitate its use as a tool for contra-lateral comparison and visual self-examination in the home environment.
A detailed discussion of LCT can be found in the publication “The Hallcrest Handbook of Thermochromic Liquid Crystal Technology” published by Hallcrest Products, Inc. of Glenview, Ill., the disclosure of which is hereby incorporated by reference in its entirety herein.